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Management of Semidwarf and Conventional
Height Oat Varieties in the Klamath Basin
R.L. Dovel and G. Chilcote l
INTRODUCTION
Oats are planted on over 10,000 acres in the Klamath Basin. Oats are well
adapted to the organic and some lacustrine soils in the county with oat yields
exceeding that of barley or wheat in some areas. Increased interest in the
production of food quality oats has resulted in recent shortages of this
commodity.
Despite the importance of this crop to Oregon, the effects of management
parameters such as fertilization, seeding rate, and planting date on oat grain
yield and quality have not been investigated. Varieties currently being
planted in the area are conventional height genotypes. The advent of high
yielding, semidwarf, lodging resistant varieties provides an opportunity to
more intensively manage these new varieties than has been possible with more
lodging-susceptible conventional varieties. Little information is available
about the value of intensive management practices for oats because lodging has
been a yield limiting factor at. both high levels of N fertilization and high
seeding rates. The development of semidwarf cultivars of wheat has lead to
the efficient use of high levels of N fertilization and other intensive
management practices that contribute to increased grain yields. Similar
benefits could result from productive semidwarf oat cultivars.
Quality oats for both food and feed command a premium price. Test weight
is currently used to assess feed and milling quality. In general, test weight
declines with increasing nitrogen fertilization rates; however, other management practices such as early planting and appropriate planting rate and row
spacing increase both yield and test weight. Increasing yield while lowering
test weight would not be economically advantageous to the producer. Thus, a
study of the effects of N fertilization and seeding rate on oat yield and
quality of both conventional and semidwarf varieties was undertaken in 1989
and 1990.
.
PROCEDURES
The effects of N fertilization and seeding rate were examined using a
factorial design with four levels of N, three seeding rates, and four oat
varieties. The experiment was arranged in a randomized complete block design
with four replications. Nitrogen as ammonium nitrate was applied at 0, 40,
80, and 120 lbs/A. A split application of 80 lbs N as ammonium nitrate at
Tlanting and 40 lbs N at flowering was also included. Seeding rates were 20,
30, and 40 seeds/square foot. Two conventional height oat varieties, Monida
and Cayuse, and two semidwarf oat varieties, Ajay and NPB 86801 were seeded.
The semidwarf line NPB 86801 will soon be released as Minimax. Seed was
planted at one-inch depth in six-inch rows.
1/ Assistant Professor and Research Technician, respectively, Klamath
Experiment Station, OR.
Acknowledgment: Financial support of this study by the Agricultural Research
Foundation is gratefully recognized.
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Data collected included time to 50 percent heading, percent lodging,plant
height, grain yield, and test weight. Plants/ft' and tillers/plant were
determined in 1990. Oat quality parameters yet to be assessed include groat
fraction and groat protein concentration.
RESULTS
There was no difference in grain yield, test weight or lodging across
years. Nitrogen fertilization affected grain yield of conventional and
semidwarf varieties differently. Grain yields of semidwarf lines increased
with increasing N fertilization to the 80 lbs N/A rate (Figure 1). In contrast, grain yields of Monida and Cayuse tended to decrease as N application
rates increased, largely due to increased lodging of the two conventional
varieties with increasing N fertilization (Figure 2). Semidwarf lines did not
experience significant lodging at any N fertilization level. The effect of
lodging was also apparent in grain test weights (Figure 3). Increasing
nitrogen fertilization decreased test weights of all varieties, except Ajay,
which was unaffected.
No difference was observed in grain yield between the split N application
and either the 80 or 120 lb N applications. Late season N application
generally does not affect yield but should result in higher groat protein
contents.
The highest yields were obtained with Ajay at N rates of 40 lbs/A or
above. Resulting yields were more than 100 lbs/A greater than in the best
conventional variety/N combination.
Although both Monida and Cayuse produced higher yields than MiniMax when
no N was applied, there are few instances where this practice is followed.
The addition of 30-50 lbs N/A banded at seeding, a common practice, would
result in the highest yields obtained in this study when planting Ajay and
MiniMax.
Seeding rate did not significantly affect yield; however, seeding rate
affected lodging of conventional and semidwarf varieties differently (Table
1). Increasing seeding rates increased lodging in both conventional height
varieties, yet had little or no effect on lodging of the two semidwarf
varieties. Although seeding rate affected lodging of conventional varieties,
the increased lodging was not sufficient to significantly reduce yield.
Since identical seeding rates were used for all varieties, the numbers of
plants per square foot reflects the relative seedling vigor of the various
varieties in the trial. Ajay and Cayuse had more plants/ft' than Monida or
Minimax (Table 2). Minimax had the lowest plant population in the trial. The
varieties also had significantly different tillers/plant with Ajay having more
tillers than any other variety. This, combined with the excellent seedling
vigor of Ajay, resulted in the highest number of tillers/ft' which directly
affects grain yield (Table 2).
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Nitrogen fertilization did not significantly affect plants/ft 2 , tillers/ft% or tillers/plant (Table 3). It is interesting to note that seeding
rate did not affect tillers/ft'. As plants/ft' decreased due to decreasing
seeding rate, tillers/plant increased (Table 4).
CONCLUSION
Both semidwarf varieties responded quite differently to N fertilization
than did conventional varieties. The lodging and yield responses were similar
to those seen in short statured wheat or semidwarf barley varieties. MiniMax
yielded less than conventional varieties at very low N levels (no N fertilization), but was equivalent to or superior when receiving some N fertilization.
Ajay was equivalent to or superior to conventional varieties at all N fertilization levels. Due to the lodging resistance and high yield potential (even
at low N levels) of Ajay this could be a very good variety selection. It
appears that the use of semidwarf varieties in high N situations would be
advisable.
Seeding rate did not affect yield in this trial. However, due to increased lodging of conventional varieties at higher seeding rates, a seeding
rate of 30 plants/ft' is advisable.
Figure 1.
6500
Effect of N fertilization on oat yield
of semi-dwarf and conventional oat
varieties at KES - 1989-1990
YIELD (LBS/A)
6000
6600
6000
4500
4000
3600
3000
0
20
40
60
80
100
120
N FERTILIZATION (LBS/A)
MAY
I
- -
MINIMAX
MONIDA
CAYUSE
140
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Figure 2. N fertilization effects on lodging of
semi-dwarf and conventional oat
varieties at KES - 1989-1990
LODGING (%)
40
80
120
N FERTILIZATION (lbs/A)
AJAY
Figure 3.
40
MINIMAX
MONIDA e CAYUSE
-
--
N fertilization effects on test weight
of semi-dwarf and conventional oat
varieties at KES 1989-1990
TEST WT (Ibs/bu)
38
38
34
32
30
0
40
80
120
N FERTILIZATION (lbs/A)
- AJAY ---4
-
MINIMAX
MONIDA
CAYUSE
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Table 1. Effect of Seeding Rate on Oats, 1989-1990. Effect of
seeding rate on oat grain yield, test weight, lodging,
and plant height averaged across 1989 and 1990. Significant interaction of seeding rate and variety examined in
Table 2, Klamath Experiment Station, OR.
Seeding Rate
seed/ft'
Yield
lbs/A
Test Wt
lbs/bu
Lodging
90
Height
cm
20
30
40
4758
4666
4607
36.1
35.6
35.7
19.8
24.5
27.6
99.2
99.8
99.0
NS
NS
NS
NS
4.5
Sig
NS
NS
LSD (0.05)
SR * Variety Interaction Table 2. Effect of Seeding Rate and Variety on Lodging. Effect of
seeding rate on lodging of various spring oats averaged
across 1989 and 1990 at the Klamath Experiment Station,
OR.
Seeding Rate
seed/ft'
.
Ajay
Minimax
Lodging %
20
30
40
0.0
0.5
1.8
0.0
0.0
0.0
LSD (0.05)
0.5
NS
Monida
38.3
54.3
63.3
Cayuse
41.0
43.3
45.3
5.8
NS
Table 3. Variety Effect on Oat Plant and Tiller Density. Varietal
effects on plants/ft% tillers/ft 2 , and tillers/plant of
spring oats planted in 1990 at Klamath Experiment Station,
OR.
Tillers
/plant
Variety
Plants
/ft'
Tillers
/ft'
Ajay
Minimax
Monida
Cayuse
30
24
27
29
62
44
48
53
2.2
1.9
1.8
1.9
28
2.2
52
3.8
2.0
0.14
Mean:
LSD (0.05)
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Table 4. Nitrogen Fertilization Effect on Oat Plant and Tiller
Density.
Nitrogen fertilization effects on plants/ft%
tillers/ft 2 , and tillers/plant of spring oats planted in
1990 at Klamath Experiment Station, OR.
Nitrogen
lbs/A
Plants
/ft'
Tillers
/ft'
Tillers
/plant
0
40
80
120
120 (80+40)
28
28
27
29
26
52
52
54
51
52
1.9
2.0
2.0
1.9
2.0
LSD (0.05)
NS
NS
NS
Table 5. Seeding Rate Effects on Oat Plant and Tiller Counts.
Seeding rate effects on plants/ft 2 , tillers/ft% and
tillers/plant of spring oats planted in 1990 at Klamath
Experiment Station, OR.
Nitrogen
lbs/A
Plants
/ft'
Tillers
/ft'
Tillers
/plant
20
30
40
21
28
33
49
53
54
2.3
1.9
1.7
LSD (0.05)
2.0
3.3
0.1